XRISM/Xtend Transient Search (XTS) detected an X-ray flare from a YSO candidate
ATel #17067; K. Fukushima, K. Hayashi, Y. Kanemaru, S. Ogawa, T. Yoshida (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), T. Kohmura (TUS), Y. Maeda (JAXA), M. Mizumoto (UTEF), N. Nagashima (Chuo U.), M. Nobukawa (NUE), K. Pottschmidt (UMBC, NASA GSFC, CRESST), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), Y. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yanagi (Chuo U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Osaka U.)
on 7 Mar 2025; 11:30 UT
Credential Certification: Kotaro Fukushima (kxfukushima@gmail.com)
Subjects: X-ray, Transient, Variables, Young Stellar Object
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1718-3711 on 2025-03-06 TT. The source position is determined to be (R.A., Dec.) = (259.375, -37.183), with a systematic error of ∼ 40 arcsec. A Plausible counterpart is an X-ray source 2CXO J171728.2-371120, which corresponds to YSO candidates Gaia DR3 5973684576802979712 or Gaia DR3 5973684572499673216. Gaia DR3 5973684576802979712 and Gaia DR3 5973684572499673216 are located ∼ 30 arcsec apart from the position of XRISM J1718-3711. All statistical uncertainties in this report will be provided as a 90% confidence level unless stated otherwise.
The flare started on 2025-03-06 at 08:31 TT. The flare rapidly peaked on 2025-03-06 at 08:40 TT. The flare exponentially decayed in 1.5 (+0.4/-0.3) × 104 sec, which is derived by fitting the 0.4 – 2.0 keV light curve with a constant + burst model in the QDP software package.
In order to estimate the source flux, we fit the spectrum in the flare phase with an absorbed APEC model with a temperature of kT = 1.8 (+0.7/-0.3) keV and a hydrogen column density NH < 7 × 1020 cm-2. Then, the model flux is calculated as (1.6 +/- 0.2) × 10-12 erg s-1 cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to the statistical error. Corresponding luminosity is (3.3 +/- 0.4) D2133 pc × 10 30 erg s-1.
We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimated the systematic error for the source position from the separations between the detected sources with the corresponding counterparts in the same field of view.
